1. I have an allergy to penicillin.
    我对青霉素有过敏反应。

1. 过敏反应：简单来说,过敏反应(allergy)乃是我们体内免疫系统对於外来物质所产生的不正确反应所导致的现象. 人体内免疫系统的基本功能除了可帮助我们抵抗外来病原体的入侵之外,尚有衡维持恒定以及监视的重要功能.

1. 过敏反应；过敏症
    If you have a particular allergy, you become ill or get a rash when you eat, smell, or touch something that does not normally make people ill.

    e.g. Food allergies can result in an enormous variety of different symptoms...
           食物过敏会引发很多不同的症状。
    e.g. Allergy to cats is one of the commonest causes of asthma.
           对猫类过敏是哮喘病发作最常见的诱因之一。

2. 厌恶；反感
    If you say that you have an allergy to something or someone, you mean that you dislike them very strongly and try to avoid them.

    e.g. I developed a temporary allergy to the company of couples.
           我一时间很反感和情侣们在一起。

1. hypersensitivity reaction to a particular allergen
    symptoms can vary greatly in intensity

    Synonym: allergic reaction